E' un po' lungo quindi mi limito alle prime due form, ma il problema è uguale. Il primo si invia regolarmente mentre il secondo da l'errore nullo o non è un oggetto. Ecco il codice:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3c.org/TR/1999/REC-html401-19991224/loose.dtd">
<HEAD><TITLE>Gli espositori di FOTOWEB</TITLE>
<link href="css/tre_colonne.css" rel="stylesheet" type="text/css">
<SCRIPT language=javascript src="java/vari.js">
</SCRIPT>
<script language="JavaScript" type="text/JavaScript">
<!--
function callJS(jsStr) { //v2.0
return eval(jsStr)
}
//-->
</script>
</HEAD>
<BODY onLoad="display_time_in_status_line()">

<DIV id=header>
<TABLE width="100%">
<tr><td rowspan="2"><H1>FOTOWEB</H1></td><td align="right"><form method=post name=form2 action=trova.php><font size=1 face='Verdana, Arial, Helvetica, sans-serif'>Testo contenuto nell'articolo</font></td></tr><tr>
<td align="right" valign="top">
<input name=trova type=text>
</td>
<td valign="middle"><img src=image/trova.gif border=0 style='CURSOR: hand' onClick="callJS('document.form2.submit()')"></td>
</tr></TABLE>

</DIV>
<HR>

<DIV id=colonna-sx>
<DIV class=box>
<H3>Espositori</H3>
</DIV></DIV>
<HR>

<DIV id=principale>
<DIV class=box>
<H3>Presentazione</H3>



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</p>
<H3>I nostri ultimi 5 articoli</H3>



</P></DIV></DIV>
<HR>

<DIV id=colonna-dx>
<DIV class=box>

<H3>colonna-dx</H3>
<FORM action="personale.php" method="POST" name="form3">
<table width="90%" border="0" cellpadding="4" cellspacing="4">
<tr><td><font size=1 face='Verdana, Arial, Helvetica, sans-serif' color="White">User name</font> <INPUT type="text" name="user"></td></tr>
<tr><td><font size=1 face='Verdana, Arial, Helvetica, sans-serif' color="White">Password</font> <INPUT type="password" name="pwd"></tr></td>
<tr><td><img src=image/login.gif border=0 style='CURSOR: hand' onClick="callJS('document.form3.submit()')"></tr></td></TABLE></FORM>
Lorem ipsum dolor sit . </DIV></DIV>
<HR>

<DIV id=footer>FOTOWEB. </DIV></BODY></HTML>